Scenarios and high level sequence diagrams
The following scenarios are used for the analysis:
- Single valid payment
- Single invalid payment
- Valid batch payment
- Invalid batch payment
The following figure shows a high level summary of the single valid payment scenario.
Figure 1. Single valid payment scenario: high level sequence diagram

The following figure shows a high level summary of the single invalid payment scenario.
Figure 2. Single invalid payment scenario: high level sequence diagram

The following figure shows a high level summary of the valid batch payment scenario.
Figure 3. Valid batch payment scenario: high level sequence diagram

The following figure shows a high level summary of the invalid batch payment scenario.
Figure 4. Invalid batch payment scenario: high level sequence diagram
